And both granddaughters and grandsons tended to have greater bone mass and lean muscle mass.

The study was carried out in Britain and published in the American Journal of Human Biology and suggests the effects of smoking during pregnancy can span generations.

Senior author Professor Marcus Pembrey said: 'These likely transgenerational effects from the grandmothers' smoking in pregnancy need to be taken into account in future studies of the effects of maternal smoking on child growth and development.

'If replicated, such studies could be a useful model for the molecular analysis of human transgenerational responses.'

NHS guidelines warn that smoking during pregnancy can increase the risk of a baby being stillborn, make it more likely that it will be born early and make it less able to cope with any birth complications.